Glutaraldehyde-preserved bioprostheses have been associated with important long-term clinical problems such as stenosis, biodegradation and calcification-induced heart failure. An alternative to the use of glutaraldehyde is proposed which consists of cross-linking biological tissue by forming stable bonds. Preliminary data suggest that this new process cross-links porcine heart valve leaflets at levels similar to glutaraldehyde. In addition, the treated leaflets are significantly more resistant to calcification than glutaraldehyde-preserved leaflets. The objective of the proposed research is to further develop this process to optimize its efficacy and safety. The specific aims of the proposal are to: i( determine the level of tissue cross-linking by quantification of residual amines, shrinkage temperature, collagenase and pronase digestion tests, ii) determine calcification of leaflets using the subdermal rat implant model, iii) evaluate the structural effects by light and scanning electron microscopy studies, and iv) evaluate the biocompatibility of treated leaflets. These experiments will be performed using four different treatment conditions from which a single condition will be selected for further development based on the results. This new fixation process could represent an important step in the field of heart valve and other bioprostheses by increasing their clinical durability.